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From:   Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To:     stefan.wahren@i2se.com, eric@anholt.net,
        dave.stevenson@raspberrypi.org
Cc:     linux-rpi-kernel@lists.infradead.org, gregkh@linuxfoundation.org,
        linux-arm-kernel@lists.infradead.org, devel@driverdev.osuosl.org,
        linux-kernel@vger.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Subject: [PATCH 11/16] staging: vchiq: use completions instead of semaphores
Date:   Wed, 14 Nov 2018 13:59:37 +0100
Message-Id: <20181114125942.25163-12-nsaenzjulienne@suse.de>
In-Reply-To: <20181114125942.25163-1-nsaenzjulienne@suse.de>
References: <20181114125942.25163-1-nsaenzjulienne@suse.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

It is preferred in the kernel to avoid using semaphores to wait for
events, as they are optimised for the opposite situation; where the
common case is that they are available and may block only occasionally.
FYI see this thread: https://lkml.org/lkml/2008/4/11/323.

Also completions are semantically more explicit in this case.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 .../interface/vchiq_arm/vchiq_arm.c           |  60 ++++++-----
 .../interface/vchiq_arm/vchiq_core.c          | 100 +++++++++---------
 .../interface/vchiq_arm/vchiq_core.h          |  26 ++---
 .../interface/vchiq_arm/vchiq_util.c          |  16 +--
 .../interface/vchiq_arm/vchiq_util.h          |   6 +-
 5 files changed, 106 insertions(+), 102 deletions(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 1cdfdb714abc..383013a92939 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -44,7 +44,7 @@
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
 #include <linux/bug.h>
-#include <linux/semaphore.h>
+#include <linux/completion.h>
 #include <linux/list.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
@@ -121,9 +121,9 @@ typedef struct user_service_struct {
 	int message_available_pos;
 	int msg_insert;
 	int msg_remove;
-	struct semaphore insert_event;
-	struct semaphore remove_event;
-	struct semaphore close_event;
+	struct completion insert_event;
+	struct completion remove_event;
+	struct completion close_event;
 	VCHIQ_HEADER_T * msg_queue[MSG_QUEUE_SIZE];
 } USER_SERVICE_T;
 
@@ -138,8 +138,8 @@ struct vchiq_instance_struct {
 	VCHIQ_COMPLETION_DATA_T completions[MAX_COMPLETIONS];
 	int completion_insert;
 	int completion_remove;
-	struct semaphore insert_event;
-	struct semaphore remove_event;
+	struct completion insert_event;
+	struct completion remove_event;
 	struct mutex completion_mutex;
 
 	int connected;
@@ -562,7 +562,8 @@ add_completion(VCHIQ_INSTANCE_T instance, VCHIQ_REASON_T reason,
 		vchiq_log_trace(vchiq_arm_log_level,
 			"%s - completion queue full", __func__);
 		DEBUG_COUNT(COMPLETION_QUEUE_FULL_COUNT);
-		if (down_interruptible(&instance->remove_event) != 0) {
+		if (wait_for_completion_interruptible(
+					&instance->remove_event)) {
 			vchiq_log_info(vchiq_arm_log_level,
 				"service_callback interrupted");
 			return VCHIQ_RETRY;
@@ -600,7 +601,7 @@ add_completion(VCHIQ_INSTANCE_T instance, VCHIQ_REASON_T reason,
 	insert++;
 	instance->completion_insert = insert;
 
-	up(&instance->insert_event);
+	complete(&instance->insert_event);
 
 	return VCHIQ_SUCCESS;
 }
@@ -673,7 +674,8 @@ service_callback(VCHIQ_REASON_T reason, VCHIQ_HEADER_T *header,
 			}
 
 			DEBUG_TRACE(SERVICE_CALLBACK_LINE);
-			if (down_interruptible(&user_service->remove_event)
+			if (wait_for_completion_interruptible(
+						&user_service->remove_event)
 				!= 0) {
 				vchiq_log_info(vchiq_arm_log_level,
 					"%s interrupted", __func__);
@@ -705,7 +707,7 @@ service_callback(VCHIQ_REASON_T reason, VCHIQ_HEADER_T *header,
 		}
 
 		spin_unlock(&msg_queue_spinlock);
-		up(&user_service->insert_event);
+		complete(&user_service->insert_event);
 
 		header = NULL;
 	}
@@ -745,7 +747,7 @@ static void close_delivered(USER_SERVICE_T *user_service)
 		unlock_service(user_service->service);
 
 		/* Wake the user-thread blocked in close_ or remove_service */
-		up(&user_service->close_event);
+		complete(&user_service->close_event);
 
 		user_service->close_pending = 0;
 	}
@@ -867,7 +869,7 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		if (status == VCHIQ_SUCCESS) {
 			/* Wake the completion thread and ask it to exit */
 			instance->closing = 1;
-			up(&instance->insert_event);
+			complete(&instance->insert_event);
 		}
 
 		break;
@@ -948,9 +950,9 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 				instance->completion_remove - 1;
 			user_service->msg_insert = 0;
 			user_service->msg_remove = 0;
-			sema_init(&user_service->insert_event, 0);
-			sema_init(&user_service->remove_event, 0);
-			sema_init(&user_service->close_event, 0);
+			init_completion(&user_service->insert_event);
+			init_completion(&user_service->remove_event);
+			init_completion(&user_service->close_event);
 
 			if (args.is_open) {
 				status = vchiq_open_service_internal
@@ -1007,7 +1009,8 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		   has been closed until the client library calls the
 		   CLOSE_DELIVERED ioctl, signalling close_event. */
 		if (user_service->close_pending &&
-			down_interruptible(&user_service->close_event))
+			wait_for_completion_interruptible(
+				&user_service->close_event))
 			status = VCHIQ_RETRY;
 		break;
 	}
@@ -1182,7 +1185,8 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 			DEBUG_TRACE(AWAIT_COMPLETION_LINE);
 			mutex_unlock(&instance->completion_mutex);
-			rc = down_interruptible(&instance->insert_event);
+			rc = wait_for_completion_interruptible(
+						&instance->insert_event);
 			mutex_lock(&instance->completion_mutex);
 			if (rc != 0) {
 				DEBUG_TRACE(AWAIT_COMPLETION_LINE);
@@ -1310,7 +1314,7 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		}
 
 		if (ret != 0)
-			up(&instance->remove_event);
+			complete(&instance->remove_event);
 		mutex_unlock(&instance->completion_mutex);
 		DEBUG_TRACE(AWAIT_COMPLETION_LINE);
 	} break;
@@ -1350,8 +1354,8 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			do {
 				spin_unlock(&msg_queue_spinlock);
 				DEBUG_TRACE(DEQUEUE_MESSAGE_LINE);
-				if (down_interruptible(
-					&user_service->insert_event) != 0) {
+				if (wait_for_completion_interruptible(
+					&user_service->insert_event)) {
 					vchiq_log_info(vchiq_arm_log_level,
 						"DEQUEUE_MESSAGE interrupted");
 					ret = -EINTR;
@@ -1373,7 +1377,7 @@ vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		user_service->msg_remove++;
 		spin_unlock(&msg_queue_spinlock);
 
-		up(&user_service->remove_event);
+		complete(&user_service->remove_event);
 		if (header == NULL)
 			ret = -ENOTCONN;
 		else if (header->size <= args.bufsize) {
@@ -1979,8 +1983,8 @@ vchiq_open(struct inode *inode, struct file *file)
 
 		vchiq_debugfs_add_instance(instance);
 
-		sema_init(&instance->insert_event, 0);
-		sema_init(&instance->remove_event, 0);
+		init_completion(&instance->insert_event);
+		init_completion(&instance->remove_event);
 		mutex_init(&instance->completion_mutex);
 		mutex_init(&instance->bulk_waiter_list_mutex);
 		INIT_LIST_HEAD(&instance->bulk_waiter_list);
@@ -2033,12 +2037,12 @@ vchiq_release(struct inode *inode, struct file *file)
 
 		/* Wake the completion thread and ask it to exit */
 		instance->closing = 1;
-		up(&instance->insert_event);
+		complete(&instance->insert_event);
 
 		mutex_unlock(&instance->completion_mutex);
 
 		/* Wake the slot handler if the completion queue is full. */
-		up(&instance->remove_event);
+		complete(&instance->remove_event);
 
 		/* Mark all services for termination... */
 		i = 0;
@@ -2047,7 +2051,7 @@ vchiq_release(struct inode *inode, struct file *file)
 			USER_SERVICE_T *user_service = service->base.userdata;
 
 			/* Wake the slot handler if the msg queue is full. */
-			up(&user_service->remove_event);
+			complete(&user_service->remove_event);
 
 			vchiq_terminate_service_internal(service);
 			unlock_service(service);
@@ -2059,7 +2063,7 @@ vchiq_release(struct inode *inode, struct file *file)
 			!= NULL) {
 			USER_SERVICE_T *user_service = service->base.userdata;
 
-			down(&service->remove_event);
+			wait_for_completion(&service->remove_event);
 
 			BUG_ON(service->srvstate != VCHIQ_SRVSTATE_FREE);
 
@@ -2103,7 +2107,7 @@ vchiq_release(struct inode *inode, struct file *file)
 
 				/* Wake any blocked user-thread */
 				if (instance->use_close_delivered)
-					up(&user_service->close_event);
+					complete(&user_service->close_event);
 				unlock_service(service);
 			}
 			instance->completion_remove++;
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
index 5791c2b670fa..a45cdd08e209 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
@@ -376,7 +376,7 @@ mark_service_closing_internal(VCHIQ_SERVICE_T *service, int sh_thread)
 
 	/* Unblock any sending thread. */
 	service_quota = &state->service_quotas[service->localport];
-	up(&service_quota->quota_event);
+	complete(&service_quota->quota_event);
 }
 
 static void
@@ -432,9 +432,9 @@ remote_event_wait(VCHIQ_STATE_T *state, REMOTE_EVENT_T *event)
 		event->armed = 1;
 		dsb(sy);
 		if (!event->fired) {
-			if (down_interruptible(
-					(struct semaphore *)
-					((char *)state + event->event)) != 0) {
+			if (wait_for_completion_interruptible(
+					(struct completion *)
+					((char *)state + event->event))) {
 				event->armed = 0;
 				return 0;
 			}
@@ -451,7 +451,7 @@ static inline void
 remote_event_signal_local(VCHIQ_STATE_T *state, REMOTE_EVENT_T *event)
 {
 	event->armed = 0;
-	up((struct semaphore *)((char *)state + event->event));
+	complete((struct completion *)((char *)state + event->event));
 }
 
 static inline void
@@ -581,7 +581,7 @@ reserve_space(VCHIQ_STATE_T *state, size_t space, int is_blocking)
 
 		/* If there is no free slot... */
 
-		if (down_trylock(&state->slot_available_event) != 0) {
+		if (!try_wait_for_completion(&state->slot_available_event)) {
 			/* ...wait for one. */
 
 			VCHIQ_STATS_INC(state, slot_stalls);
@@ -592,13 +592,13 @@ reserve_space(VCHIQ_STATE_T *state, size_t space, int is_blocking)
 			remote_event_signal(&state->remote->trigger);
 
 			if (!is_blocking ||
-				(down_interruptible(
-				&state->slot_available_event) != 0))
+				(wait_for_completion_interruptible(
+				&state->slot_available_event)))
 				return NULL; /* No space available */
 		}
 
 		if (tx_pos == (state->slot_queue_available * VCHIQ_SLOT_SIZE)) {
-			up(&state->slot_available_event);
+			complete(&state->slot_available_event);
 			pr_warn("%s: invalid tx_pos: %d\n", __func__, tx_pos);
 			return NULL;
 		}
@@ -678,7 +678,7 @@ process_free_queue(VCHIQ_STATE_T *state, BITSET_T *service_found, size_t length)
 					/* Signal the service that it
 					** has dropped below its quota
 					*/
-					up(&service_quota->quota_event);
+					complete(&service_quota->quota_event);
 				else if (count == 0) {
 					vchiq_log_error(vchiq_core_log_level,
 						"service %d message_use_count=%d (header %pK, msgid %x, header->msgid %x, header->size %x)",
@@ -703,7 +703,7 @@ process_free_queue(VCHIQ_STATE_T *state, BITSET_T *service_found, size_t length)
 						/* Signal the service in case
 						** it has dropped below its
 						** quota */
-						up(&service_quota->quota_event);
+						complete(&service_quota->quota_event);
 						vchiq_log_trace(
 							vchiq_core_log_level,
 							"%d: pfq:%d %x@%pK - slot_use->%d",
@@ -744,7 +744,7 @@ process_free_queue(VCHIQ_STATE_T *state, BITSET_T *service_found, size_t length)
 					count - 1;
 			spin_unlock(&quota_spinlock);
 			if (count == state->data_quota)
-				up(&state->data_quota_event);
+				complete(&state->data_quota_event);
 		}
 
 		/*
@@ -754,7 +754,7 @@ process_free_queue(VCHIQ_STATE_T *state, BITSET_T *service_found, size_t length)
 		mb();
 
 		state->slot_queue_available = slot_queue_available;
-		up(&state->slot_available_event);
+		complete(&state->slot_available_event);
 	}
 }
 
@@ -862,8 +862,8 @@ queue_message(VCHIQ_STATE_T *state, VCHIQ_SERVICE_T *service,
 			spin_unlock(&quota_spinlock);
 			mutex_unlock(&state->slot_mutex);
 
-			if (down_interruptible(&state->data_quota_event)
-				!= 0)
+			if (wait_for_completion_interruptible(
+						&state->data_quota_event))
 				return VCHIQ_RETRY;
 
 			mutex_lock(&state->slot_mutex);
@@ -873,7 +873,7 @@ queue_message(VCHIQ_STATE_T *state, VCHIQ_SERVICE_T *service,
 			if ((tx_end_index == state->previous_data_index) ||
 				(state->data_use_count < state->data_quota)) {
 				/* Pass the signal on to other waiters */
-				up(&state->data_quota_event);
+				complete(&state->data_quota_event);
 				break;
 			}
 		}
@@ -893,8 +893,8 @@ queue_message(VCHIQ_STATE_T *state, VCHIQ_SERVICE_T *service,
 				service_quota->slot_use_count);
 			VCHIQ_SERVICE_STATS_INC(service, quota_stalls);
 			mutex_unlock(&state->slot_mutex);
-			if (down_interruptible(&service_quota->quota_event)
-				!= 0)
+			if (wait_for_completion_interruptible(
+						&service_quota->quota_event))
 				return VCHIQ_RETRY;
 			if (service->closing)
 				return VCHIQ_ERROR;
@@ -1251,7 +1251,7 @@ notify_bulks(VCHIQ_SERVICE_T *service, VCHIQ_BULK_QUEUE_T *queue,
 					waiter = bulk->userdata;
 					if (waiter) {
 						waiter->actual = bulk->actual;
-						up(&waiter->event);
+						complete(&waiter->event);
 					}
 					spin_unlock(&bulk_waiter_spinlock);
 				} else if (bulk->mode ==
@@ -1274,7 +1274,7 @@ notify_bulks(VCHIQ_SERVICE_T *service, VCHIQ_BULK_QUEUE_T *queue,
 			}
 
 			queue->remove++;
-			up(&service->bulk_remove_event);
+			complete(&service->bulk_remove_event);
 		}
 		if (!retry_poll)
 			status = VCHIQ_SUCCESS;
@@ -1667,7 +1667,7 @@ parse_rx_slots(VCHIQ_STATE_T *state)
 				service->remoteport = remoteport;
 				vchiq_set_service_state(service,
 					VCHIQ_SRVSTATE_OPEN);
-				up(&service->remove_event);
+				complete(&service->remove_event);
 			} else
 				vchiq_log_error(vchiq_core_log_level,
 					"OPENACK received in state %s",
@@ -1721,7 +1721,7 @@ parse_rx_slots(VCHIQ_STATE_T *state)
 				"%d: prs CONNECT@%pK", state->id, header);
 			state->version_common = ((VCHIQ_SLOT_ZERO_T *)
 						 state->slot_data)->version;
-			up(&state->connect);
+			complete(&state->connect);
 			break;
 		case VCHIQ_MSG_BULK_RX:
 		case VCHIQ_MSG_BULK_TX:
@@ -2055,7 +2055,7 @@ sync_func(void *v)
 				vchiq_set_service_state(service,
 					VCHIQ_SRVSTATE_OPENSYNC);
 				service->sync = 1;
-				up(&service->remove_event);
+				complete(&service->remove_event);
 			}
 			release_message_sync(state, header);
 			break;
@@ -2194,33 +2194,33 @@ vchiq_init_state(VCHIQ_STATE_T *state, VCHIQ_SLOT_ZERO_T *slot_zero)
 		initialize events and mutexes
 	 */
 
-	sema_init(&state->connect, 0);
+	init_completion(&state->connect);
 	mutex_init(&state->mutex);
-	sema_init(&state->trigger_event, 0);
-	sema_init(&state->recycle_event, 0);
-	sema_init(&state->sync_trigger_event, 0);
-	sema_init(&state->sync_release_event, 0);
+	init_completion(&state->trigger_event);
+	init_completion(&state->recycle_event);
+	init_completion(&state->sync_trigger_event);
+	init_completion(&state->sync_release_event);
 
 	mutex_init(&state->slot_mutex);
 	mutex_init(&state->recycle_mutex);
 	mutex_init(&state->sync_mutex);
 	mutex_init(&state->bulk_transfer_mutex);
 
-	sema_init(&state->slot_available_event, 0);
-	sema_init(&state->slot_remove_event, 0);
-	sema_init(&state->data_quota_event, 0);
+	init_completion(&state->slot_available_event);
+	init_completion(&state->slot_remove_event);
+	init_completion(&state->data_quota_event);
 
 	state->slot_queue_available = 0;
 
 	for (i = 0; i < VCHIQ_MAX_SERVICES; i++) {
 		VCHIQ_SERVICE_QUOTA_T *service_quota =
 			&state->service_quotas[i];
-		sema_init(&service_quota->quota_event, 0);
+		init_completion(&service_quota->quota_event);
 	}
 
 	for (i = local->slot_first; i <= local->slot_last; i++) {
 		local->slot_queue[state->slot_queue_available++] = i;
-		up(&state->slot_available_event);
+		complete(&state->slot_available_event);
 	}
 
 	state->default_slot_quota = state->slot_queue_available/2;
@@ -2354,8 +2354,8 @@ vchiq_add_service_internal(VCHIQ_STATE_T *state,
 	service->service_use_count = 0;
 	init_bulk_queue(&service->bulk_tx);
 	init_bulk_queue(&service->bulk_rx);
-	sema_init(&service->remove_event, 0);
-	sema_init(&service->bulk_remove_event, 0);
+	init_completion(&service->remove_event);
+	init_completion(&service->bulk_remove_event);
 	mutex_init(&service->bulk_mutex);
 	memset(&service->stats, 0, sizeof(service->stats));
 
@@ -2470,7 +2470,7 @@ vchiq_open_service_internal(VCHIQ_SERVICE_T *service, int client_id)
 			       QMFLAGS_IS_BLOCKING);
 	if (status == VCHIQ_SUCCESS) {
 		/* Wait for the ACK/NAK */
-		if (down_interruptible(&service->remove_event) != 0) {
+		if (wait_for_completion_interruptible(&service->remove_event)) {
 			status = VCHIQ_RETRY;
 			vchiq_release_service_internal(service);
 		} else if ((service->srvstate != VCHIQ_SRVSTATE_OPEN) &&
@@ -2622,7 +2622,7 @@ close_service_complete(VCHIQ_SERVICE_T *service, int failstate)
 			if (is_server)
 				service->closing = 0;
 
-			up(&service->remove_event);
+			complete(&service->remove_event);
 		}
 	} else
 		vchiq_set_service_state(service, failstate);
@@ -2663,7 +2663,7 @@ vchiq_close_service_internal(VCHIQ_SERVICE_T *service, int close_recvd)
 					vchiq_set_service_state(service,
 						VCHIQ_SRVSTATE_LISTENING);
 			}
-			up(&service->remove_event);
+			complete(&service->remove_event);
 		} else
 			vchiq_free_service_internal(service);
 		break;
@@ -2672,7 +2672,7 @@ vchiq_close_service_internal(VCHIQ_SERVICE_T *service, int close_recvd)
 			/* The open was rejected - tell the user */
 			vchiq_set_service_state(service,
 				VCHIQ_SRVSTATE_CLOSEWAIT);
-			up(&service->remove_event);
+			complete(&service->remove_event);
 		} else {
 			/* Shutdown mid-open - let the other side know */
 			status = queue_message(state, service,
@@ -2805,7 +2805,7 @@ vchiq_free_service_internal(VCHIQ_SERVICE_T *service)
 
 	vchiq_set_service_state(service, VCHIQ_SRVSTATE_FREE);
 
-	up(&service->remove_event);
+	complete(&service->remove_event);
 
 	/* Release the initial lock */
 	unlock_service(service);
@@ -2837,11 +2837,11 @@ vchiq_connect_internal(VCHIQ_STATE_T *state, VCHIQ_INSTANCE_T instance)
 	}
 
 	if (state->conn_state == VCHIQ_CONNSTATE_CONNECTING) {
-		if (down_interruptible(&state->connect) != 0)
+		if (wait_for_completion_interruptible(&state->connect))
 			return VCHIQ_RETRY;
 
 		vchiq_set_conn_state(state, VCHIQ_CONNSTATE_CONNECTED);
-		up(&state->connect);
+		complete(&state->connect);
 	}
 
 	return VCHIQ_SUCCESS;
@@ -2936,7 +2936,7 @@ vchiq_close_service(VCHIQ_SERVICE_HANDLE_T handle)
 	}
 
 	while (1) {
-		if (down_interruptible(&service->remove_event) != 0) {
+		if (wait_for_completion_interruptible(&service->remove_event)) {
 			status = VCHIQ_RETRY;
 			break;
 		}
@@ -2997,7 +2997,7 @@ vchiq_remove_service(VCHIQ_SERVICE_HANDLE_T handle)
 		request_poll(service->state, service, VCHIQ_POLL_REMOVE);
 	}
 	while (1) {
-		if (down_interruptible(&service->remove_event) != 0) {
+		if (wait_for_completion_interruptible(&service->remove_event)) {
 			status = VCHIQ_RETRY;
 			break;
 		}
@@ -3054,7 +3054,7 @@ VCHIQ_STATUS_T vchiq_bulk_transfer(VCHIQ_SERVICE_HANDLE_T handle,
 		break;
 	case VCHIQ_BULK_MODE_BLOCKING:
 		bulk_waiter = (struct bulk_waiter *)userdata;
-		sema_init(&bulk_waiter->event, 0);
+		init_completion(&bulk_waiter->event);
 		bulk_waiter->actual = 0;
 		bulk_waiter->bulk = NULL;
 		break;
@@ -3080,8 +3080,8 @@ VCHIQ_STATUS_T vchiq_bulk_transfer(VCHIQ_SERVICE_HANDLE_T handle,
 		VCHIQ_SERVICE_STATS_INC(service, bulk_stalls);
 		do {
 			mutex_unlock(&service->bulk_mutex);
-			if (down_interruptible(&service->bulk_remove_event)
-				!= 0) {
+			if (wait_for_completion_interruptible(
+						&service->bulk_remove_event)) {
 				status = VCHIQ_RETRY;
 				goto error_exit;
 			}
@@ -3157,7 +3157,7 @@ VCHIQ_STATUS_T vchiq_bulk_transfer(VCHIQ_SERVICE_HANDLE_T handle,
 
 	if (bulk_waiter) {
 		bulk_waiter->bulk = bulk;
-		if (down_interruptible(&bulk_waiter->event) != 0)
+		if (wait_for_completion_interruptible(&bulk_waiter->event))
 			status = VCHIQ_RETRY;
 		else if (bulk_waiter->actual == VCHIQ_BULK_ACTUAL_ABORTED)
 			status = VCHIQ_ERROR;
@@ -3326,7 +3326,7 @@ vchiq_set_service_option(VCHIQ_SERVICE_HANDLE_T handle,
 					 service_quota->message_use_count)) {
 					/* Signal the service that it may have
 					** dropped below its quota */
-					up(&service_quota->quota_event);
+					complete(&service_quota->quota_event);
 				}
 				status = VCHIQ_SUCCESS;
 			}
@@ -3347,7 +3347,7 @@ vchiq_set_service_option(VCHIQ_SERVICE_HANDLE_T handle,
 					service_quota->slot_use_count))
 					/* Signal the service that it may have
 					** dropped below its quota */
-					up(&service_quota->quota_event);
+					complete(&service_quota->quota_event);
 				status = VCHIQ_SUCCESS;
 			}
 		} break;
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h
index 5b1696422e21..b76281f7510e 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h
@@ -35,7 +35,7 @@
 #define VCHIQ_CORE_H
 
 #include <linux/mutex.h>
-#include <linux/semaphore.h>
+#include <linux/completion.h>
 #include <linux/kthread.h>
 
 #include "vchiq_cfg.h"
@@ -307,8 +307,8 @@ typedef struct vchiq_service_struct {
 	VCHIQ_BULK_QUEUE_T bulk_tx;
 	VCHIQ_BULK_QUEUE_T bulk_rx;
 
-	struct semaphore remove_event;
-	struct semaphore bulk_remove_event;
+	struct completion remove_event;
+	struct completion bulk_remove_event;
 	struct mutex bulk_mutex;
 
 	struct service_stats_struct {
@@ -337,7 +337,7 @@ typedef struct vchiq_service_quota_struct {
 	unsigned short slot_use_count;
 	unsigned short message_quota;
 	unsigned short message_use_count;
-	struct semaphore quota_event;
+	struct completion quota_event;
 	int previous_tx_index;
 } VCHIQ_SERVICE_QUOTA_T;
 
@@ -410,7 +410,7 @@ struct vchiq_state_struct {
 	unsigned short default_message_quota;
 
 	/* Event indicating connect message received */
-	struct semaphore connect;
+	struct completion connect;
 
 	/* Mutex protecting services */
 	struct mutex mutex;
@@ -426,16 +426,16 @@ struct vchiq_state_struct {
 	struct task_struct *sync_thread;
 
 	/* Local implementation of the trigger remote event */
-	struct semaphore trigger_event;
+	struct completion trigger_event;
 
 	/* Local implementation of the recycle remote event */
-	struct semaphore recycle_event;
+	struct completion recycle_event;
 
 	/* Local implementation of the sync trigger remote event */
-	struct semaphore sync_trigger_event;
+	struct completion sync_trigger_event;
 
 	/* Local implementation of the sync release remote event */
-	struct semaphore sync_release_event;
+	struct completion sync_release_event;
 
 	char *tx_data;
 	char *rx_data;
@@ -481,12 +481,12 @@ struct vchiq_state_struct {
 	int unused_service;
 
 	/* Signalled when a free slot becomes available. */
-	struct semaphore slot_available_event;
+	struct completion slot_available_event;
 
-	struct semaphore slot_remove_event;
+	struct completion slot_remove_event;
 
 	/* Signalled when a free data slot becomes available. */
-	struct semaphore data_quota_event;
+	struct completion data_quota_event;
 
 	struct state_stats_struct {
 		int slot_stalls;
@@ -505,7 +505,7 @@ struct vchiq_state_struct {
 
 struct bulk_waiter {
 	VCHIQ_BULK_T *bulk;
-	struct semaphore event;
+	struct completion event;
 	int actual;
 };
 
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c
index 2e52f07bbaa9..44b954daa74a 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c
@@ -48,8 +48,8 @@ int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size)
 	queue->write = 0;
 	queue->initialized = 1;
 
-	sema_init(&queue->pop, 0);
-	sema_init(&queue->push, 0);
+	init_completion(&queue->pop);
+	init_completion(&queue->push);
 
 	queue->storage = kcalloc(size, sizeof(VCHIQ_HEADER_T *), GFP_KERNEL);
 	if (!queue->storage) {
@@ -80,7 +80,7 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header)
 		return;
 
 	while (queue->write == queue->read + queue->size) {
-		if (down_interruptible(&queue->pop) != 0)
+		if (wait_for_completion_interruptible(&queue->pop))
 			flush_signals(current);
 	}
 
@@ -100,17 +100,17 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header)
 
 	queue->write++;
 
-	up(&queue->push);
+	complete(&queue->push);
 }
 
 VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue)
 {
 	while (queue->write == queue->read) {
-		if (down_interruptible(&queue->push) != 0)
+		if (wait_for_completion_interruptible(&queue->push))
 			flush_signals(current);
 	}
 
-	up(&queue->push); // We haven't removed anything from the queue.
+	complete(&queue->push); // We haven't removed anything from the queue.
 
 	/*
 	 * Read from queue->storage must be visible after read from
@@ -126,7 +126,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue)
 	VCHIQ_HEADER_T *header;
 
 	while (queue->write == queue->read) {
-		if (down_interruptible(&queue->push) != 0)
+		if (wait_for_completion_interruptible(&queue->push))
 			flush_signals(current);
 	}
 
@@ -146,7 +146,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue)
 
 	queue->read++;
 
-	up(&queue->pop);
+	complete(&queue->pop);
 
 	return header;
 }
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h
index 5a1540d349d3..b226227fe5bc 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h
@@ -35,7 +35,7 @@
 #define VCHIQ_UTIL_H
 
 #include <linux/types.h>
-#include <linux/semaphore.h>
+#include <linux/completion.h>
 #include <linux/mutex.h>
 #include <linux/bitops.h>
 #include <linux/kthread.h>
@@ -60,8 +60,8 @@ typedef struct {
 	int write;
 	int initialized;
 
-	struct semaphore pop;
-	struct semaphore push;
+	struct completion pop;
+	struct completion push;
 
 	VCHIQ_HEADER_T **storage;
 } VCHIU_QUEUE_T;
-- 
2.19.1